Record corruption problems

[Owen Jenkins]

I have an Access 2000 app which is in use by about 20 clients on LANs
where each LAN would have between 2 and 6 PCs networked. The main form
is a tabbed form with multiple subforms. It has been in use for several
years and the only corruption issues I have had have been a few
instances of a corrupted memo field and I've been able to copy and paste
the rest of the record successfully.

After a recent update (I update the front end regularly), I have had
quite a few instances where clients have noted corrupted records where
the entire record is lost. Typically #Deleted appears in every field and
after repair & compacting, ######## appears in every field. These fields
are then easily deleted, but the data is lost. The update involved
(among other things) ensuring the subform recordsources were not set
until required, to speed up data entry. The corrupted records appear to
be random and it's usually only one record in a table of many hundreds
of records.

I've searched the newsgroup for answers regarding corruption but haven't
found anthing that has helped yet. Because it's happened to several
clients, I don't think its related to faulty NICs etc. Or, if it is, why
should I be losing entire records now, whereas in the last 5 or so
years, I've only ever lost a few memo fields?

Anyone have any ideas?

Owen Jenkins

[Larry Linson]

"Owen Jenkins" <[e-mail]>

I've searched the newsgroup for answers regarding
corruption but haven't found anthing that has helped
yet. Because it's happened to several clients, I don't
think its related to faulty NICs etc. Or, if it is, why
should I be losing entire records now, whereas in
the last 5 or so years, I've only ever lost a few
memo fields?

Could it be that just one NIC has recently "gone bad"? Or, one or more NICs
have developed intermittent errors? Doesn't take a "catastrophic event" to
cause enough of a spike to cause NIC problems. That said, although,
ungraceful degradation is a known cause of corruption, there are others --
recent software updates, perhaps a DLL involved in the O/S writing to disk,
or such.

Larry Linson
Microsoft Access MVP

But, the first place to look is your most recent update -- check carefully.

As a resource on avoiding corruption, it's hard to beat MVP Tony Toews' site
http://www.granite.ab.ca/accsmstr.htm.

Anyone have any ideas?

Owen Jenkins

[Owen Jenkins]

>Could it be that just one NIC has recently "gone bad"? Or, one or more NICs
have developed intermittent errors? Doesn't take a "catastrophic event" to
cause enough of a spike to cause NIC problems. That said, although,
ungraceful degradation is a known cause of corruption, there are others --
recent software updates, perhaps a DLL involved in the O/S writing to disk,
or such.

Larry Linson
Microsoft Access MVP

But, the first place to look is your most recent update -- check carefully.

Thanks Larry,

I don't have the ability to troubleshoot NICs, but I'll look carefully
at my update, particularly for any 'concurrency' issues. I just wish I
could reproduce the corruption on my own PCs so I could find a cause. I
suspect it is something I have caused with my coding somewhere. I've
considered all the corruption/networking posts and am not quite sure
where to go next.

[Owen Jenkins]

Thanks Larry,

>
I don't have the ability to troubleshoot NICs, but I'll look carefully
at my update, particularly for any 'concurrency' issues. I just wish I
could reproduce the corruption on my own PCs so I could find a cause.
I suspect it is something I have caused with my coding somewhere. I've
considered all the corruption/networking posts and am not quite sure
where to go next.

I've looked more closely at this and have found that I can reliably
corrupt a record by doing the following ...

Open two separate but identical front ends on one PC each linking to the
same back end.
Edit a records in one front end and leave it unsaved.
Edit the same record in the other front end and save the change.
Save the change in the first front end - this pops up the Write Conflict
message to which I click Save.
About 10-20 seconds later, all fields in the record are replaced with
|||||||||||||||||||||||||||. Sometimes this causes corruption of the
file, sometimes not.

Obviously saving a change to a record in 2 front ends is not a good
thing to do, but should it corrupt the record? What is the point of the
Write Conflict box if one of the options corrupts the record.

Strange thing is, this happens when the front and back ends are in
Access 2000 format or when the FE is 2003 and BE 2000. It never happens
when the BE is A97 format, whether the FR is A97, 2000 or 2003.

Any more ideas?

Owen